Method of manufacturing semiconductor device

Abstract

A method of manufacturing a semiconductor device, including preparing a semiconductor wafer having first and second main surfaces opposite to each other, forming a photoresist film on the first main surface of the semiconductor wafer, forming a plurality of openings at predetermined positions in the photoresist film, cleaning the semiconductor wafer with water after the openings are formed, drying the semiconductor wafer by rotating the semiconductor wafer around a center axis that is orthogonal to the first main surface of the semiconductor wafer, to thereby generate a centrifugal force to cause the water that is left in the openings of the photoresist film to fly off the semiconductor wafer, and ion-implanting a predetermined impurity by a predetermined acceleration energy from the first main surface of the semiconductor wafer, using the photoresist film as a mask, after the drying. The drying process includes setting a rotational speed of the semiconductor wafer to be at most an upper limit value.

What is claimed is: 
     
       1. A method of manufacturing a semiconductor device, the method comprising:
 preparing a semiconductor wafer, the semiconductor wafer having a first main surface and a second main surface opposite to each other; 
 a formation process including forming a photoresist film on the first main surface of the semiconductor wafer; 
 a developing process including forming a pattern of a plurality of openings at predetermined positions in the photoresist film; 
 a cleaning process including cleaning the semiconductor wafer with water after the developing process; 
 a drying process including drying the semiconductor wafer by rotating the semiconductor wafer around a center axis that is orthogonal to the first main surface of the semiconductor wafer, to thereby generate a centrifugal force to cause the water that is left in the openings of the photoresist film after the cleaning process to fly off the semiconductor wafer; and 
 an injection process including ion-implanting a predetermined impurity by a predetermined acceleration energy from the first main surface of the semiconductor wafer, using the photoresist film as a mask, after the drying process, wherein 
 the drying process includes setting a rotational speed of the semiconductor wafer to be at most an upper limit value. 
 
     
     
       2. The method according to  claim 1 , wherein
 setting the rotational speed of the semiconductor wafer includes setting the rotational speed of the semiconductor wafer such that the centrifugal force at an outer periphery of the semiconductor wafer is at most 1.2N. 
 
     
     
       3. The method according to  claim 1 , wherein
 the upper limit value of the rotational speed of the semiconductor wafer, y 1 , satisfies y 1 =−10x 1 +3650, wherein 
 x 1  is a diameter of the semiconductor wafer. 
 
     
     
       4. The method according to  claim 1 , wherein
 setting the rotational speed of the semiconductor wafer includes setting the rotational speed of the semiconductor wafer according to a volume of the openings of the photoresist film. 
 
     
     
       5. The method according to  claim 4 , wherein
 the upper limit value of the rotational speed of the semiconductor wafer, y 3 , satisfies y 3 =−16475x 2 +5640.2, where 
 x 2  is the volume of the openings of the photoresist film. 
 
     
     
       6. The method according to  claim 1 , wherein
 in the drying process, the semiconductor wafer is dried by a single rotation session. 
 
     
     
       7. The method according to  claim 1 , wherein
 the drying process further includes a first rotation session of rotating the semiconductor wafer by a first rotational speed, followed by a second rotation session of rotating the semiconductor wafer by a second rotational speed higher than the first rotational speed. 
 
     
     
       8. The method according to  claim 1 , wherein
 the formation process includes forming the photoresist film with a thickness of at least 20 μm. 
 
     
     
       9. The method according to  claim 1 , wherein
 the developing process includes forming the plurality of openings, each in a rectangular shape in a plan view of the semiconductor wafer, and having an opening area that is at least 1 mm 2 . 
 
     
     
       10. The method according to  claim 1 , wherein
 the upper limit value corresponds to a thickness of the photoresist film.